Electric discharge apparatus



Dec. 21, 1948. HfcAMpBELL V 2,456,860

ELECTRIC DIS CHARGE APPARATUS Filed April 29, 1944 Inve'ntor: John H. Campbell,

by Jab/5% His Attorney.

Patented Dec. 21, 1948 2,456,860 ELECTRIC DISCHARGE APPARATUS John New York H. Campbell, Altamont, N. Y., assignor to General Electric Company,

a corporation of Application April 29, 1944, Serial No. 533,335

2 Claims.

My invention relates to electric discharge apparatus and particularly to apparatus for starting electric discharge devices such for example as fluorescent lamps. It is the object of my invention to provide an improved form of apparatus for starting such devices which can be used successfully without preheating the electrodes of the device and which is simple in construction, involves no moving parts and is inexpensive to manufacture.

My invention will be better understood from the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

Referring to the drawing, Figs. 1 and 2 are circuit diagrams illustrating two different forms of my invention.

In Fig. 1 the electric discharge device l, which for example may be a fluorescent lamp, has the thermionic electrodes 2 and 2 at the ends thereof, the electrodes being shown as short-circuited filaments. The device is connected to be operated from the source of alternating current supply 3, which may be a 115 volt commercial lighting circuit through the control switch 4 and the ballast 5 which is represented as a reactor. The apparatus for starting the discharge device comprises the step-up autotransformer 6 whose primary 1 is connected in a series circuit with the resistor 8 across the device I. The secondary 9 of the transformer which supplies a starting voltage to the device connects between the electrode 2' and a metallic member I0 which may be a metal clamp or other conductor on or close to the wall of the device such for example as the commonly employed reflector.

When the control switch 4 is closed to operate the device the transformer 6 becomes energized and applies to the device between the member In and the electrode 2 thereof a voltage which is sufficient to cause ionization within the device and thereby cause it to break down and start. After it has started very little current traverses the primary of the transformer by reason of the reduced voltage across the device.

In the modified form of my invention shown by Fig. 2 the starting voltage produced by the secondary of the transformer 6 is applied between the electrodes 2 and 2' through the capacitor H. The construction and operation of the apparatus shown in this figure otherwise are similar to that of the form shown in Fig. 1 and described above.

What I claim as new and desire to secure by Letters Patent of the United States:

1. In combination, an electric discharge device having spaced electrodes, a ballast impedance, means connecting said device and impedance in series across a source of alternating current, and a step-up autotransformer having its primary connected in shunt with said device to be energized by current taken from said source, and a capacitor connected between only one of said electrodes and the free end of the secondary of said transformer.

2. In combination, an electric discharge device having spaced electrodes, a ballast impedance, means connecting said discharge device and impedance in series across a source of alternating current, and a step-up autotransiormer having its primary connected in shunt with said discharge device to be energized by current taken from said source and a capacitor electrically connected between only one electrode of said discharge device and the free end of the secondary of said transformer.

JOHN H. CAMPBELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

